I had a boat built and now am doing what I can in order to make sure I keep it.  I live in an area where things will walk off if not tended.

Does anyone know where to find a 5/8 locking pin (like a locking receiver pin) that is at least FIVE inches long?

I pulled the swing away tongue off of my trailer and put it into the garage, but would like to also shove a lock into one of the 5/8 inch holes on the trailer end of the connection for good measure.

Google is your friend. Check Amazon, uhaul and other trailer suppliers. Northern Tool. Rac to Supply, etc. Will likely all have them. I have one that is like that, but have had it so long that I can't recall where I got it.

I just use a long hardened master lock through the hole where the pin goes through.

Google is your friend, if you use the right search terms. So is Amazon with the right terms. It turns out the correct term for this item is "Swing Away Trailer Lock." Unfortunately, the terms I was using prior to my question included the word "receiver" and weren't getting me anything over 3 1/2 inches. When I drove to the local places so I could get it secured tonight, the guys at O'Reilly's, Menards, and Harbor Freight were less than helpful.

Here it is for anyone who has a swing away tongue they want to secure.  $20.

While I'm at it, does anyone have a good way to secure a Pro-Drive 36 to a hull beyond the bolts I already have it attached with?

Outboard padlock sets like this one don't work because of the stuff that controls the motor bounce and the hydraulics gets in the way.

I would like to rely on something other than bolts and the fact that the motor is really heavy.

How about one of these McGard lock nuts for stern drives on one or more of the mounting bolts?

That looks like it will do the trick.

Thanks!